About Powersupplies !

[frog2001]

Hello!


After reading here for some time, i thougt i´m able to clear some things up about the power problems with cheap powersupplies. I will try not to be to technical.

In the old days about 5 to 10 years ago, a powersupply for wallplugs was an big, black havy brick with a lot of copper and other meaner things in it. Quality was easily checked. If it was heavy it was good , if not it was crap.

Today it is not as easy as in the past.

After the mass appearence of the so called SMPS all changed. SMPS stand for "Switch Mode Power Supply".

The "new" kind of Powersupply has changed a lot of things.
1. It is much more efficent as the old transformator powersupplies.
2. Less powerconsumption if not used, but plugged in.
3. Today it is much cheaper to build.
4. Easy mass production

but on the other side there are

1. Very optimistic data about the usable power
2. Great potential source of electromagnetic and electronic disturbance

Ok, so why all the blah,blah.

If you have an 5 Volt 1 Ampere powersupply, you can thrust the 5 Volt. But don´t thrust about the current. If you drain more than 0.8 Ampere out of it the trouble normally starts. Because of being pushed to the limits, the normally clean and stable 5 Volt are being messed up with so called spikes.
Extremly short impulses that can mess up digital signals like the ones used in the MK8..
This can cause freezes, strange behavior, or even prevent system startup.
So it is better to use an powersupply that offers a much greater usable current.

But there is another problem with this powersupply. They are extremly poorly shielded from sending out electromagnetic waves. So if they are used in the upper limits of their usable current, they can start to mess up with the W-LAN. So if you have W-LAN issues and there are powersupplies nearby (less than an meter or so) try to get them away. You can be surprised about the results. This also counts for the W-LAN router/AP.

If you have any questions about this special theme, feel free to post your question.
If you can explain it better feel also free to post it

frog2001

[zvoddy23]

5V 2A LINEAR PSU

So where??? do you get a 5V linear PSU from these days or any days for that matter.
5volts is a relatively new standard & any older linear supplies would only have 3V, 6V , 9V , 12v etc...
A 2amp one would be brick sized & as heavy.
I would like to get my hands on one.
I have adjustable LAB PSU's 0v to 30Vdc but they won't fit behind the telly.
I could build one but i'm prone to laziness.

[frog2001]

So where??? do you get a 5V linear PSU from these days or any days for that matter.

THAT is an really good question. But maybe i have some advice.
First Think! Maybe not the most obvious thing
If something is to cheap to be true, where is the red sign saying "Gotcha"
In the case of android TV players it is obviously the accessories they put in the case.
Back to the thinking part:
How much power do i need?
As far as i know the Rikomagics need about 800mA to 1A, the experiance of the years has shown that it is an good idea to double the needed power. The benefits are, that even if you use all power you need you are well aroude the 50% mark, if you use a 2A PSU. Thats great. Your PSU stays cold, and you are not running into trouble.
How much do i have to spend?
Don´t buy the cheapest part. Take one of the midfield, so you have a good chance to get one thats worth the money.
For the USB Wallplugs a 5V/2A fits right for the sticks. If you don´t buy the cheapest the chance is very good that it is not a 5V/1A with an sticker on it claiming its an 2A.

5volts is a relatively new standard & any older linear supplies would only have 3V, 6V , 9V , 12v etc...
A 2amp one would be brick sized & as heavy.

You are right . It´s really overkill but you can buy universal notebook PSU with exchangeable output from 1.8 to 36V. But i doesn´t think it´s nessesary to have 5V with about 20A. It has the size of an smaller external USB harddisk, so it would fit behind the TV.

I have adjustable LAB PSU's 0v to 30Vdc but they won't fit behind the telly.
I could build one but i'm prone to laziness.

make a hole in the wall behind the TV. It will fit.

Just joking.

frog2001

[Felix1220]

You can also use a PSU with something like 9V or 12V or.....
just buy from **** a KIS-3R33S modul, they are very cheap - sometimes less then $1 one
just google for KIS-3R33S, its a stepdown regulator
remove the tiny cap and the diode (X) with a nailclip or desolder it if you can.
solder 2 caps with around 47µ or 100µ and a Pot with around 50k - adjust to 5V
thats it - you have 5V with 3A (peak 4A)
the circuit on my picture is very simple, if you want to make it better to adjust,you need few parts more

[boyzie]

So could I use a power supply with say 10amps and outputs 5volts without blowing the device up? Does too many amps matter? I've always wondered about this.

[Felix1220]

Does too many amps matter?

you cant have "too many amps"
the device will only take what it needs from the PSU
but you can have too many volt, and this can blow your device
If you worry about the ampere, just put an simple fuse between the PSU and your device

[boyzie]

Ok thanks,will dig out my universal power adapter........

[zvoddy23]

You can also use a PSU with something like 9V or 12V or.....
just buy from **** a KIS-3R33S modul, they are very cheap - sometimes less then $1 one
just google for KIS-3R33S, its a stepdown regulator
remove the tiny cap and the diode (X) with a nailclip or desolder it if you can.
solder 2 caps with around 47µ or 100µ and a Pot with around 50k - adjust to 5V
thats it - you have 5V with 3A (peak 4A)
the circuit on my picture is very simple, if you want to make it better to adjust,you need few parts more

[ATTACH=CONFIG]1731[/ATTACH]

Thanx for that...This is very usefull info....Igot some MPS chips from china recently to fix a led display, and i still have a spare.
Not sure if i totaly trust trimpots though as they could drift over time....Maybe adjust then find equivalent ohms to hard-wire in.
Do these module have to be adjusted while under load or unloaded???

[Felix1220]

my english is not really good, so i cant explain well.
I adjust without load and its ok, but you can check under load to be sure
in the picture before the pot is not really linear.
I made an other one, this is better.
but you must choose between few potentiometers, they all have a big tolerance (usually around +/- 20%)
here you can adjust between 3 and 5 volts
if you need 5 Volt only you must calculate the resistors
also you can use the enable pin for a switch if you need

EDIT: I forgot... if you need more then 3 Ampere you can use the TexasInstruments module PTR08060W for 6 Amp, its also very simple to build
http://www.ti.com/product/ptr08060w

[zvoddy23]

my english is not really good, so i cant explain well.
I adjust without load and its ok, but you can check under load to be sure
in the picture before the pot is not really linear.
I made an other one, this is better.
but you must choose between few potentiometers, they all have a big tolerance (usually around +/- 20%)[ATTACH=CONFIG]1742[/ATTACH]
here you can adjust between 3 and 5 volts
if you need 5 Volt only you must calculate the resistors
also you can use the enable pin for a switch if you need


EDIT: I forgot... if you need more then 3 Ampere you can use the TexasInstruments module PTR08060W for 6 Amp, its also very simple to build
http://www.ti.com/product/ptr08060w

Das ist uberwunderbar her felix....mein deutsche ist einen schitzen ..No??

3A should be enough for my MX1....I'll try to obtain one of these modules....Thanx again.

[Felix1220]

Das ist uberwunderbar her felix....mein deutsche ist einen schitzen ..No??

sound better then my english

I am one of those freaks they vape instead of smoking
we use chips like this to build our own devices.
if you want to go with the TI chip you can read about here
--> http://www.e-cigarette-forum.com/for...ltage-mod.html
If you have luck, TI will send you one for a free sample

I hope its ok to link to this page

[leolas]

Thanks frog2001, great post, people usually forgot how important is the PSU in any device. If you can copy and paste it here in general cause this advice is usefull for all tv sticks and for any etectronical device. Or if you give me your permission i will add a link to this one here:

http://www.freaktab.com/showthread.php?3805-Stability-issues-and-power-supply

[lukesan]

zvody23 you can buy them pre-made on ****. I bought one to test and have a couple on order now.

http://www.****.co.uk/itm/3905070039...84.m1497.l2649

I have all the right equipment at home, but for that price I am not going to bother making it anymore.
Measured the output on a scope and it looks fairly clean. Also not to much noise on the spectrum analyzer so this module alone doesn't cause any issues using wifi.

[zvoddy23]

zvody23 you can buy them pre-made on ****. I bought one to test and have a couple on order now.

http://www.****.co.uk/itm/3905070039...84.m1497.l2649

I have all the right equipment at home, but for that price I am not going to bother making it anymore.
Measured the output on a scope and it looks fairly clean. Also not to much noise on the spectrum analyzer so this module alone doesn't cause any issues using wifi.

That's even better.......prefab for the exact purpose......Great stuff lukesan

[frog2001]

Or if you give me your permission i will add a link to this one here:
http://www.freaktab.com/showthread.p...d-power-supply

@leolas: Feel free to do so!

I wouldn´t mind, if this post is pulled in an other part of the forum by a mod or admin, but then i probably loose track of it.
Like out of sight, was there something ?
I only have a single tasking brain, multitasking is evil

@Felix1220: I´m vaping too. Do you order the modules directly in china? That was the reason i never really startet to build something own

@boyzie: As Felix1220 said it doesn´t matter. Think of tow tanks one with 1000l of water and the other of 2000l. The Pipe you use to get the water (or curret) stands for the voltage. If you get 10l in 1 minute out of the 1000l, you will get 10l in 1min out of the 2000l. It´s a silly comparison, but i learned that our trainees understand this the best way.

@lukesan: Thanks for the link. Great finding.


frog2001